Disclosed herein is a humidification device for a fuel cell. The humidification device for a fuel cell, which performs membrane humidification of exhaust gas exhausted from a cathode of a fuel cell and dried air supplied through an air compressor and supplies the humidified air to the cathode, includes: a main membrane module including several bundles of first hollow-fiber membranes disposed in the main membrane module and a sub-membrane module connected to the main membrane module and including several bundles of second hollow fiber membranes disposed in the sub-membrane module.